The present invention relates generally to interface devices for allowing humans to interface with computer systems, and more particularly to computer interface devices that allow the user to provide input to computer systems and allow computer systems to provide force feedback to the user.
Users interact with computer systems for a variety of reasons. A computer system typically displays a visual environment to a user on a display output device. Using an interface device, a user can interact with the displayed environment to perform functions and tasks on the computer, such as playing a game, experiencing a simulation or virtual reality environment, using a computer aided design system, operating a graphical user interface (GUI), or otherwise influencing events or images depicted on the screen. Common human-computer interface devices used for such interaction include a joystick, mouse, trackball, stylus, tablet, pressure-sensitive ball, or the like, that is connected to the computer system controlling the displayed environment. Typically, the computer updates the environment in response to the user""s manipulation of a user-manipulatable physical object such as a joystick handle or mouse, and provides visual and audio feedback to the user utilizing the display screen and audio speakers. The computer senses the user""s manipulation of the user object through sensors provided on the interface device that send locative signals to the computer. For example, the computer displays a cursor, controlled vehicle, or other graphical object in a graphical environment, where the location or motion of the graphical object is responsive to the to the motion of the user object. The user can thus control the graphical object by moving the user object.
In some interface devices, tactile and/or haptic feedback is also provided to the user, more generally known as xe2x80x9cforce feedback.xe2x80x9d These types of interface devices can provide physical sensations which are felt by the user manipulating a user manipulable object of the interface device. For example, the Force-FX joystick controller from CH Products, Inc. and Immersion Corporation may be connected to a computer and provides forces to a user of the controller. Other systems might use a force feedback mouse controller. One or more motors or other actuators are coupled to the joystick or other user object and are connected to the controlling computer system. The computer system controls forces on the joystick in conjunction and coordinated with displayed events and interactions by sending control signals or commands to the actuators. The computer system can thus convey physical force sensations to the user in conjunction with other supplied feedback as the user is grasping or contacting the joystick or other object of the interface device. For example, when the user moves the manipulatable object and causes a displayed cursor to interact with a different displayed graphical object, the computer can issue a command that causes the actuator to output a force on the user object, conveying a feel sensation to the user.
A problem with the prior art development of force feedback sensations in software is that the programmer of force feedback applications does not have an intuitive sense as to how forces will feel when adjusted in certain ways, and thus must go to great effort to develop characteristics of forces that are desired for a specific application. For example, a programmer may wish to create a specific spring and damping force sensation between two graphical objects, where the force sensation has a particular stiffness, play, offset, etc. In current force feedback systems, the programmer must determine the parameters and characteristics of the desired force by a brute force method, by simply setting parameters, testing the force, and adjusting the parameters in an iterative fashion. This method is cumbersome because it is often not intuitive how a parameter will affect the feel of a force as it is actually output on the user object; the programmer often may not even be close to the desired force sensation with initial parameter settings. Other types of forces may not be intuitive at all, such as a spring having a negative stiffness, and thus force sensation designers may have a difficult time integrating these types of sensations into software applications. Thus, a tool is needed for assisting the programmer or developer in intuitively and easily setting force feedback characteristics to provide desired force sensations.
The present invention is directed to designing force sensations output by a force feedback interface device. A controlling host computer provides a design interface tool that allows intuitive and simple design of a variety of force sensations.
More particularly, a design interface for designing force sensations for use with a force feedback interface device is described. The force sensation design interface is displayed on a display device of a host computer. Input from a user is received in the interface, where the input selects a type of force sensation to be commanded by a host computer and output by a force feedback interface device. Input, such as parameters, is then received from a user which designs and defines physical characteristics of the selected force sensation. A graphical representation of the characterized force sensation is displayed on a display device of the host computer. The graphical representation provides the user with a visual demonstration of a feel of the characterized force sensation such that said user can view an effect of parameters on said force sensation. The characterized force sensation is output to a user manipulatable object of the force feedback interface device such that the user can feel the designed force sensation. The graphical representation is updated in conjunction with the force sensation being output on the user object, promoting further understanding of the effects of the characterization on the output force sensation. The user can preferably input additional changes to the characterized forces sensation after experiencing the feel of the sensation and feel the changed force sensation. Thus, in an iterative process, the user can design effective force sensations through actual experience of those sensations. The user can preferably store the characterization or parameters of the designed force sensation to a storage medium that can be accessed by other programs on the host computer or other computers. Other programs that control force feedback can thus utilize the designed force sensation in applications such as games, simulations, or graphical interfaces.
A wide variety of types of force sensations can be designed in the interface tool of the present invention. Described types include conditions, effects, and dynamics. Some force sensations include a simple mode of graphical representation that is more intuitive but offers less control over parameters that an advanced mode. In the advanced mode, a force versus user object motion profile is displayed, where the user may adjust parameters of the selected force sensation by dragging displayed control points of the profile. Represented force sensations include a damping condition, a spring condition, a slope condition, a texture condition, and periodic waves. The user can also design compound force sensations including multiple single force sensations. For example, a preferred graphical representation of a slope condition includes a hill image and a ball image, where the user moves the ball with the user object. The force on the ball provided by a negative spring stiffness is intuitively analogized by the visual representation of the ball rolling down the hill and feeling the appropriate forces. In one embodiment, the force feedback interface device includes a microprocessor separate from the host computer system. The microprocessor receives commands from the host computer system, reads sensors of the interface device and reports positions of said user object to the host computer, and commands actuators of the interface device to output the force sensation on the user object.
The present invention advantageously provides a simple, easy-to-use design interface tool for designing force feedback sensations. Given the large variety of possible force sensations and the often unexpected results when modifying the several parameters of force sensations, the design interface tool of the present invention meets the needs of force sensation designers that wish to create force sensations as close to their needs as possible. The graphical design interface of the present invention allows a force sensation programmer or developer to easily and intuitively design force sensations, conveniently experience the designed force sensations, and visually understand the effect of changes to different aspects of the force sensations.
These and other advantages of the present invention will become apparent to those skilled in the art upon a reading of the following specification of the invention and a study of the several figures of the drawing.